栽培耐旱的茶樹（Camellia sinensis）可為解決日益頻繁且嚴重的乾旱問題提供一個永續性方法，然而，目前對茶樹耐旱分子遺傳機制的了解有限，致使此方法的執行仍然困難。本研究旨在比較具親緣關係但乾旱耐受性不同的四個茶樹品種，在缺水處理下彼此間的轉錄體調控差異，並且找出與耐旱相關的潛在分子標誌。分析結果顯示，參與苯丙素類生合成、抗氧化酶和主動穿膜運輸系統的基因表現量，在耐旱品種顯著升高，暗示著茶樹藉由累積二次代謝產物和抗氧化酶來防禦因缺水所導致的氧化壓力。此外，bZIP、bHLH、NAC、AP2/ERF、MYB、和WRKY等可能調控乾旱反應和抗氧化物生合成相關基因表現的轉錄因子，在耐旱茶樹品種缺水前後的表現量有顯著差異，在非耐旱品種則不然。從四個茶樹品種間的親緣關係可推導出位於蛋白質序列編碼區的34,426個非同義的單點核苷酸多型性位點（SNP）和1,184個插入/缺失，其中28個SNP座落於14個與耐旱性有關的關鍵轉錄因子基因上，更顯示這些遺傳變異作為遺傳標誌的潛能。本研究所得到的結果為茶樹耐旱性的分子機制提供新見解，並且在為了改良茶樹品種特性而進行遺傳操控和標記輔助篩選時，提供了重要基因體資訊。;Breeding for drought adaptation in tea plants, Camellia sinensis, is a sustainable way to address the emerging issues of more frequent and severe droughts. However, this task remains difficult due to limited understanding of the genetic basis of drought tolerance in tea. This study aimed to investigate the transcriptomic profiles of four genetically-related tea cultivars differing in drought responses (tolerant and sensitive) under dehydration treatment and discover putative molecular markers associated with drought tolerance. Genes involved in salicylic biosynthesis and signal transduction, phenylpropanoid biosynthetic pathways, transmembrane transport systems were significantly up-regulated in tolerant cultivars, suggesting the accumulation of secondary metabolites induced by salicylic acid as an antioxidative defensive mechanism during water-deficit condition in tea. Additionally, several transcription factors (bZIP, bHLH, NAC, AP2/ERF, MYB, WRKY) probably engaging in the regulation of drought-responsive gene expression and biosynthetic pathways of antioxidants were differentially expressed in tolerant but not sensitive cultivars. A total of 34426 non-synonymous SNPs and 1184 InDels located on protein coding regions were inferred from the genetic inheritance of the four tea cultivars. Among these, 28 SNPs were characterized from 14 key transcription factors related to drought tolerance, highlighting their potential implications as genetic markers for genotyping in tea. These results provide novel insight of drought-defensive responses at molecular level and genomic resources for genetic manipulation and marker-assisted selection in tea crop improvement.
